Accumulation of a multi-component mixture of pesticides in soil, plants, bee organisms, and beekeeping products

Abstract

Environmental pollution worldwide is systemic in nature and is associated with the use of pesticides from various groups as plant protection products. Agricultural pesticides accidentally affect beneficial, non-target insects, particularly the honeybee (Apis mellifera L.), which leads to mass poisoning and contamination of beekeeping products with toxic compounds. The aim of the research was to determine the accumulation of pesticides from different groups in soil, plants, dead bees, and beekeeping products in apiaries in various regions of Ukraine during the mass deaths of bee colonies in 2021–2022. Pesticide content in biological samples was determined using liquid mass spectrometry (UPLC-MS/MS) and gas mass spectrometry (GC-MS/MS). The main pesticides that contaminate the soil, plants, and beekeeping products, causing the death of bee colonies, are insecticides and fungicides in various combinations. In isolated cases, bee colony deaths were registered from a single insecticide. More often, two or more pesticides were found in the soil, plants, dead bees, and beekeeping products. The total list of detected pesticides in soils, grain, plant biomass, bees, brood, bee bread, and honey included 23 compounds. The maximum number of pesticides forming a cocktail in biological samples included 5 substances. Most frequently, pesticide combinations that contaminated the soil and plants and caused bee deaths included insecticides from the pyrethroid group: lambda-cyhalothrin and cypermethrin, and from the neonicotinoid group: clothianidin and imidacloprid, as well as fungicides from the triazole group: tebuconazole, cyproconazole, and strobilurins: azoxystrobin in various concentrations. The cause of bee poisoning was the contamination of the inflorescences of non-target crops, such as maple and meadow grasses, as well as wind-pollinated and self-pollinated crops, including wheat, peas, soybeans, and potatoes, located within the flight radius of bees. Among entomophilous plants, rapeseed and sunflower were the main crops, the pesticide treatment of which contributed to soil contamination, plant biomass, and bee poisoning during honey collection. It was found that the concentration of certain pesticides in dead bees reached, and in some cases exceeded, the acute oral toxic dose LD50 by tens of times. The results of the research could form the basis for determining the cumulative toxicity of combinations of different pesticides for beneficial insects and for developing biological plant protection products